Turbo-jet engine for aircraft



APIil 6 1943- A. G. slLvl-:srER 2,439,273

TURBO-JET ENGINE FOR AIRCRAFT PROPULSION Filed lax-ch 20, 1944 Austin G.Silvester'.

Patented Apr. 6, 1948 TURBO-JET ENGINE FOR AIRCRAFT PROPULSION Austin G.Silvester, Danvers, Mass., assignor to General Electric Company, avcorporation of New York Application March 20, 1944, SerialNo. 527,159

1 Claim. (CI. 60-35.6)

The present invention relates to aircraft power plants and especially topower 'plants which function to effect travel of the aircraft by meansof a jet of gas discharged into the atmosphere. This is termed usuallyjetspropulsion.

The object of my invention is to provide an improved construction andarrangement of jet propulsion aircraft vpower plant, andfor a consideration of what I believe to be novel and my invention, attention isdirected to the following specification and to the claim appendedthereto.

In the drawing, Fig. l is a perspective view of an aircraft equippedwith two power plants embodying my invention, and Fig. 2 is a sectionalview through one of the power plants.

Referring first to Fig. 2, I indicates a shaft mounted in a suitablebearing structure 2, the bearing being enclosed in a bearing housing 3.In the present instance, the bearing structure comprises two ballbearings spaced axially at cpposite ends of the bearing housing. Mountedon the left hand end of shaft I is an impeller 4 of a centrifugalcompressor, the impeller being held in place on the shaft by a nut 5.The vanes of the impeller are indicated at 8, the inlet to the vanes isindicated at 1, and the discharge ends of the vanes are indicated at` 8.Surrounding the impeller are walls which define a diffuser 9, the curvedvanes of the diffuser being indicated at I0. This is a known type ofcentrifugal compressor and isl to be taken as typical of any suitablecompressor arrangement.

On the other end of shaft I is mounted a turbine wheel II on the rim ofwhich is a ring of turbine a disk I 5 which functions as a shield toprotect the turbine wheel from the heat of adjacent parts. f

Surrounding the compressor and turbine and suitably supported on thecasings of the compressor and turbine are a series of combustion unitsor chambers I8. The combustion units or chambers are spacedcircumferentially relatively to each other and may comprise any suitablenumber. Each combustion unit comprises an outer circular tapered casingwall I1 within which is mounted a burner tube I8 of suitable diameter,it being supported in spaced relation to outer casing wall I1 bysuitable means such as, for example, the spacing clips I9 which supportits right hand end and the fuel tube 20 which supports its left handend. Between casing wall I1 the end head of burner tube I8 is a suitablefuel I nozzle 24 to which fuel is ,supplied through fuel tube 20. Thefuel tubes 2llof the several burners are connected to an annular supplypipe 25 which in turn is supplied with fuel through a fuel pipe ,i line26 which connects with the discharge side of a suitable pump 21 driventhrough gearing (not shown) connected with shaft I. The suction inlet ofpump 2l is connected by a` pipe line 28 to a suitable fuel supply tank.Each combustion unit may be provided with an ignition-plug 28a for` usein starting. 'I'he combustion unit illustrated is shown onlydiagrammatically. `Preferab1y, I employ a unit of the type morespecifically disclosed in the application of Anthony J. Nerad, SerialNo. 501,106, filed September 2, 1943, and assigned to thesame assigneeas the present invention. At 29 is a combined lubricating pump I andscavenging pump, it being in substance two pumps built into a singlecasing. The lubricating pump takes lubricant froma suitable source ofsupply which may be in the housing 30 which encloses the pumps anddelivers. it through a pipe line 3I to the bearings through the passagesindicated in the bearing housing. Oil from the bearings accumulates in asump 32 from which it is pumped by the scavenging pump back to thesupply chamber through a suction pipe line 33. Casing 30 may `containalso suitable auxiliaries for the turbo compressor set such as astarting motor and a generator (not shown).

The gases discharged to exhaust chamber I4 are conveyed by a suitableconduit 35 to a thermal jet pump comprising a combined injector, dif-Afuser and a jet discharge nozzle. The injector comprises an outwardlycurved wall 36 which faces in the direction of motion of the aircraftBeyond throat 31 as regards the direction of ow throughthe structure isan outwardly tapering wall which forms a diffuser 38 and beyonddiffuser38 is an inwardly tapering wall which forms a discharge nozzle39. Conduit 35 terminatesin a discharge nozzle 4I) located at the throat`3", and in spaced Y relation to the wall of the throat to define anannular air admission passage vIllia. `It willbe seen thatcurved wall3G, throat `3,"` and diffuser 38 form in substance a 4Venturi tube.Surrounding diffuser 38 at its discharge end is a wall II which definesan annular chamber 42 surrounding the diffuser. Chamber 42 is connectedto the interior of the diffu-ser by a series of rows of spaced holes 43,this forming in substance a screen separating chamber 42 from thediluser. Chamber 42 is connected to the inlet of impeller 4 by a conduit44.

In connection with discharge nozzle 39, I may provide an augmentercomprising a ,series of bell mouthed augmenter tubes 45 connected toeach other and to the end of discharge nozzle 39 by suitable webs 46.The tubes 45 are nested as shown, the bell-shaped mouths of tubes 45facing in the direction of motion; and each is adapted for flow of airfromrits forward or entrance end 41 to its discharge end 48. Nozzle 39discharges into the first of the augmenter tubes and it in turndischarges into the next following augmenter tube. Any suitable numberof successive augmenter tubes may be used, three being shown in thepresent instance.

One or more units, as shown in Fig. 2, may be suitably mounted on anaircraft for effecting travel of the aircraft by jet propulsion. In thepresent instance, I have shown in Fig. 1 two such units, one on each'side of the fuselage 50 of an aircraft. The power plant proper,including the power plant turbo-compressor unit, may be mounted in asuitable nacelle 5I on the side of which is a wall 52 which includes thestructure comprising the injector, the diffuser, the discharge nozzleand the jet augmenters, The conduit 35 extends out through wall 5l andprojects into the ejector, as shown in Fig. 1. At 53 is a. wall whichdefines an opening 54 which faces in the direction of motion and throughwhich airis supplied to the jet augmenters. It will be understood thatthe arrangement in any particular case depends upon the structure of theaircraft and the number of power units tov be mounted thereon. When thepower plant is in operation, the aircraft being propelled through theair, air is rammed into the funnel-shaped inlet 36 of the Venturi tube.Its flow is augmented by gases disch'arged from the end 40 of conduit 35which gases are discharged at considerable velocity. 'Ihe mixture ofgases and air which ows through throat 31 enters the diffuser 38 at highvelocity and in the diffuser its Velocity is converted into pressure toa considerable extent. For example, about 90% of the velocity may beconverted into pressure. Accordingly, there is provided at th'e largerportion of diffuser 38 where chamber 42 is formed, a region of higherpressure. At this region is a mixture of air and turbine exhaust gases.Some of the air and gases pass through openings 43 to chamber 42 fromwhich they are conveyed through conduit 44 to the impeller, From theimpeller, the mixture of air and gases is supplied to the severalcombustion units I6. Here, fuel is supplied to the mixture of y air andgases which is burned and the products of combustion supplied to thebuckets 4I2 of the turbine wheel through the nozzles I3. The portion ofthe mixture of air and gases not taken by the compressor rand this mayrepresent the major portion) is discharged through the tapered dischargenozzle 39 directly to atmosphere to effect jet propulsion of th'eaircraftv in a well understood manner.

In the operation oft a combustion chamber, as shown, there is providedalways a large excess of air. Accordingly, the gases which are mixedwith the air supplied to the burners do not affect adversely combustionin the combustion chamber, there being still ample oxygen for completecombustion. At the same time. the temperature of the gases entering thecompressor are relatively low in temperature.

With the above-described arrangement, the mixture of air and gasessupplied to the impeller 4 is at a pressure well above atmosphericpressure. 'Ihis means that the compressor does not have to do as muchwork as would be the case were the supply to it at atmospheric pressure.Accordingly, a smaller compressor and a smaller turbine may be usedbecause the impeller has to do less work in bringing the substancepumped by it up to the desired pressure for use in the burners.

Viewed from one aspect, it may be considered that I have a two-stagecompressor, the first `stage being in the form of a jet compressoractuated by t e gases discharged from the turbine wheel an the secondstage being in the form of a compressor driven by the turbine wheelwhich in turn is actuated by gases from the combustion units. Inotherwords, the gases from the combustion units are utilized rst in aturbine wheel to drive a compressor, then in a jet injector to initiallycompress air to be supplied to the inlet of the compressor operated bythe turbine and then used as a propulsion means for th'e aircraft.

What I claim as new and desire to secure b Letters Patent of the UnitedStates is: v In a gas turbine powerplant for the jet propulsion ofaircraft, the combination of a turbocompressor including a compressorimpeller and a turbine rotor mounted on a common shaft arrangedsubstantially parallel to the direction of flight with the turbine rotorat the forward end thereof, a combustion chamber arranged sub'4Astantially axially of the turbo-compressor and adapted at its rearwardportion to receive uid from the compressor and to deliver h'ot gases tothe turbine rotor from the forward end thereof, and a thermal jet pumpactuated by the hot gases discharged .from the turbine, said jet pumpincluding an elongated housing of circular crosssection having a flaredair inlet portion open to the atmosphere and facing forward in thedirection of flight, said housing also defining a, constricted throatportion, an expanding diffusing portion and a rearwardly directedpropulsion nozzle in series iiow relation with the air inlet portion,Inozzle means supported in said constricted throat portion and directedrearwardly, conduit means for conducting gases discharged from theturbine to said nozzle means, said jet pump housing having a perforatedportion in the high pressure region intermediate the diffusing portionand the propulsion nozzle, and conduit means surrounding said perforatedportion and adapted to conduct fluid from said high pressure region tothe inlet of said compressor impeller, whereby the jet pump provides arst stage of compression in series with the compressor and also forms amain propulsion nozzle.

AUSTIN G. SILVESTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,182,665 Eynon et al. May 9,1916 2,168,726 Whittle Aug. 8, 1939 FOREIGN PATENTS Number Country Date299,420 Great Britain May V15, 1930

